1. Field of the Invention
The present invention relates to an anti-lifting mechanism for preventing a motor vehicle from being lifted up at the rear portion of the body frame thereof when the brake is applied.
2. Description of the Prior Art
When the brake is applied for decelerating or stopping a motor vehicle, for example, a two-wheeled motor vehicle, the front portion of the vehicular body frame comes down, the rear portion thereof is lifted up and the rear wheel tends to float from the road surface, due to a frictional force between the road surface and the wheels and a moment about the vehicular center of gravity induced by a forward shift thereof because of the force of inertia. A known device for preventing such a tail lifting phenomenon, is disclosed in Japanese Utility Model Laid Open Publication No. 31990/1981 which utilizes a braking force of the rear wheel, as illustrated in FIG. 17 of the accompanying drawings.
In FIG. 17, a rear fork 501 supports a rear wheel 503 at its rear end and hence serves as a rear wheel supporting member, and its front end is vertically pivotably connected to a body frame 500 through a pivot shaft 502. Rotatably supported by the rear fork 501 is a brake disc 504 serving as a brake member coaxial and integral with the rear wheel 503. Furthermore, a bracket 506 which holds a brake caliper 505 is pivotably attached to the rear fork 501 about an axle 503a of the rear wheel 503. A brake caliper 505, together with the bracket 506, constitutes a braking means; that is, a hydraulically operated brake pad is brought into pressure contact with the brake disc 504 to brake the rear wheel 503 to thereby decelerate or stop the motor vehicle. The body frame 500 and the bracket 506 are interconnected through a link means 508 which comprises a single torque rod 507. When the rear wheel 503 is braked by the brake caliper 505, the bracket 506 pivots in a counterclockwise direction in FIG. 17 about the axle 503a, whereby a rearward tensile force is exerted on the torque rod 507, and by virtue of this tensile force the front and the rear portion of the body frame 500 are prevented from coming down and being lifted up, respectively. At this instant, a reaction of the tensile force of the torque rod 507 against the body frame 500, which is a relatively stationary member, acts on the relatively pivotable rear fork 501 through the pivot shaft 502 as a counterclockwise moment M in FIG. 17. Accordingly it is necessary to produce the counterclockwise moment M on the rear fork in order to attain an anti-lifting effect.
In the prior art arrangement described above, because the torque link means 508 is constituted by a single torque rod 507 for producing the moment M on the rear fork 501, it is necessary that the torque rod 507 cross the rear fork 501 when viewed from the side and that, as shown in FIG. 17, a connecting position A between the body frame 500 and the torque rod 507 and a connecting position B between the bracket 506 and the torque rod 507 be made opposite to each other in the vertical direction with respect to the rear fork 501. In such a construction, it would be impossible to pass the straight torque rod 507 through a clearance S formed between the rear fork 501 and the rear wheel 503 because the clearance S is very small, as shown in FIG. 18, and for this reason it is inevitably necessary to use a bent torque rod 507', 507" or 507" as shown in FIGS. 17 and 18 to avoid interference with the rear fork 501 and the rear wheel 503. In this case, however, the torque rod becomes insufficient in strength against the load exerted thereon, thus causing a problem in torque transmission between the body frame 500 and the bracket 506 and further causing a likelihood of deformation of the torque rod.
The present invention has been attained in order to effectively overcome the above-mentioned problems of the conventional anti-lifting mechanism.